They have an interesting setup - there is no land ownership other than by the state, and you can only get permission to build by winning a lottery. There are minor exceptions for building small hunting cabins in the fjords, but this is negligible. The reason is to prevent private ownership from hindering possible opportunities for the state in the future.
So, why a good call?
Climate change.
1) Greenland has vast reserves of fresh water. This resource will become increasingly valuable as clean fresh water grows scarcer globally.
2) agriculture and habitation. If Greenland continues to melt, in centuries to come there will be vast planes of glacial till - good, fertile land. As the climate warms, the arctic waste will potentially become far more hospitable than (dis)temperate latitudes.
3) strategic dominance. The Arctic is going to be exceedingly important as ice clears for both transportation and resource extraction. Greenland has vast untapped mineral reserves, never mind the territorial waters.